Crude vegetable oils obtained from either pressing or solvent extraction methods are a complex mixture of triacylglycerols, phospholipids, sterols, tocopherols, free fatty acids, trace metals, and other minor compounds. It is desirable to remove the phospholipids, free fatty acids and trace metals in order to produce a quality edible oil.
In soybean oil processing, the soy seed may first be flaked before hexane extraction to obtain a flake oil. In another commonly known process, the seed is first treated by an expander before extraction, resulting in an expander oil. The latter usually leads to higher oil yield, but also to a higher phospholipid content. Other oils such as canola or rapeseed oil are first pressed leading to the pressed oil fraction. The press cake can be further treated with a solvent to yield an extracted oil fraction and the two fractions combined are known as crude oil for canola, rapeseed or sunflower.
The removal of phospholipids generates the majority of losses associated with the degumming of vegetable oils. Since most phospholipid molecules possess both a hydrophilic functional group and a lipophilic moiety consisting of a glycerol with two fatty acid chains, they tend to be excellent natural emulsifiers. The major phospholipids in vegetable oils are phosphatidyl choline (PC), phosphatidyl ethanolamine (PE), phosphatidyl inositol (PI) and phosphatidic acid (PA). The removal of phospholipids is known as degumming of vegetable of oils.
Various processes are known for enzymatic degumming of vegetable oils, using enzymes with phospholipase activity, such as phospholipase A1, phospholipase A2, phospholipase C, or phosphatidyl inositol phospholipase C activity.
WO 2011046812 discloses the use of a PI-PLC in an enzymatic degumming process. The vegetable oil is first treated with an acid followed by neutralization with an alkali after which enzymatic degumming takes place. The enzymatically treated oil is centrifuged to separate the oil from the water phase.
U.S. Pat. No. 7,713,727 B2 discloses a process for reducing fouling of oil processing equipment wherein the edible vegetable oil is treated with a phospholipase enzyme, wherein after the enzyme reaction, the oil is treated with an organic acid.
U.S. Pat. No. 8,460,905 B2 discloses a process for enzymatic degumming of a seed oil, such as soybean oil, wherein a phospholipase C and a phospholipase A are contacted with the oil under neutral or acid conditions.
WO 2014/090161 discloses a process for enzymatic degumming of a seed oil, such as soybean oil using a phospholipase C, wherein the oil is pre-treated with an acid and a base.
There is a need for an improved process for enzymatic degumming of a vegetable oil.